Lead frame, light emitting diode having the lead frame, and backlight unit having the light emitting diode

ABSTRACT

An LED includes a light-emitting chip, a metal member, and a housing. The light-emitting chip generates light. The light-emitting chip is arranged on the metal member. The housing is combined with the metal member to fix the metal member. The housing has an opening portion exposing at least a portion of the light-emitting chip and the metal member. The metal member includes a base metal layer, a light-reflecting layer arranged on the base metal layer, and a protection layer arranged on the light-reflecting layer and including a metal.

CROSS REFERENCE TO RELATED APPLICATION

This application is a divisional of U.S. patent application Ser. No.12/351,480, filed Jan. 9, 2009, and claims priority from and the benefitof Korean Patent Application No. 2008-122152, filed on Dec. 3, 2008, andKorean Patent Application No. 2008-129036, filed on Dec. 18, 2008, whichare hereby incorporated by reference for all purposes as if fully setforth herein.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a lead frame, a light emitting diodehaving the lead frame, and a backlight unit having the light emittingdiode. More particularly, the present invention relates to a lead frameof high optical reflectivity and reliability, a light emitting diodehaving the lead frame, and a backlight unit having the light emittingdiode.

2. Discussion of the Background

In general, a light emitting diode (LED) converts electric energy intolight by using compound semiconductor. The LED has merits such as a highefficiency, a long life span, and low power consumption. Furthermore,the LED is eco-friendly. Therefore, the LED may be used in variousfields.

The LED may be formed by packaging a light-emitting chip mounted on alead frame. When electric power is applied to the light-emitting chipthrough the lead frame, the light-emitting chip emits light.

According to a conventional LED, a lead frame coated with silver (Ag) isused in order to enhance light reflectivity. However, the lead framecoated with silver (Ag) may be vulnerable to moisture and heat, so thatwhen the LED is used for a long time, the lead frame is corroded anddarkened to lower luminance and shorten life span. In order to solve thecorrosion problem, a lead frame coated with gold (Au) instead of silverwas developed, but gold (Au) has relatively low light reflectivity thatmay lower efficiency of an LED.

SUMMARY OF THE INVENTION

The present invention provides a lead frame having high reflectivitywhile minimizing corrosion and discoloration.

The present invention also provides a light emitting diode (LED) havingthe lead frame to have high reflectivity.

The present invention also provides a backlight unit having the LED.

Additional features of the invention will be set forth in thedescription which follows, and in part will be apparent from thedescription, or may be learned by practice of the invention.

The present invention discloses a lead frame including a base metallayer, a light-reflecting layer, and a protection layer. Thelight-reflecting layer is arranged on the base metal layer. Theprotection layer is arranged on the light-reflecting layer and includesa metal.

The present invention also discloses an LED including a light-emittingchip, a metal member, and a housing. The light-emitting chip generateslight. The light-emitting chip is arranged on the metal member. Thehousing is combined with the metal member to fix the metal member. Thehousing has an opening portion exposing at least a portion of thelight-emitting chip and the metal member. The metal member includes abase metal layer, a light-reflecting layer arranged on the base metallayer, and a protection layer arranged on the light-reflecting layer andincluding a metal.

The present invention also discloses a backlight unit including a lightguide plate and at least one light emitting diode (LED) providing thelight guide plate with light. The LED includes a lead frame including abase metal layer, a light-reflecting layer arranged on the base metallayer, and a protection layer arranged on the light-reflecting layer andincluding a metal, and a light-emitting chip mounted on the lead frame.The light-reflecting layer includes silver (Ag) or aluminum (Al). Theprotection layer includes gold (Au), nickel (Ni), or titanium (Ti).

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory and areintended to provide further explanation of the invention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention and are incorporated in and constitute apart of this specification, illustrate embodiments of the invention, andtogether with the description serve to explain the principles of theinvention.

FIG. 1 is a plan view showing a light emitting diode according to anexemplary embodiment of the present invention.

FIG. 2 is a cross-sectional view taken along line I-I′ in FIG. 1.

FIG. 3 is an enlarged view showing a lead frame in FIG. 2.

FIG. 4 is a graph showing a relationship between a thickness of theprotection layer of gold (Au) and efficiencies of the light emittingdiode in FIG. 1.

FIG. 5 is a graph showing a relationship between a thickness of theprotection layer of nickel (Ni) and titanium (Ti) and lighttransmittances.

FIG. 6 is a cross-sectional view showing a lead frame according toanother exemplary embodiment of the present invention.

FIG. 7 is a cross-sectional view showing an LED according to anotherexemplary embodiment of the present invention.

FIG. 8 is a plan view showing a portion of an LED according to stillanother exemplary embodiment of the present invention.

FIG. 9 is a cross-sectional view taken along line A-A′ in FIG. 8.

FIG. 10 is a cross-sectional view taken along line B-B′ in FIG. 8.

FIG. 11 is a cross-sectional view taken along line C-C′ in FIG. 8.

FIG. 12 is a plan view for showing a process of making first and secondlead terminals according to an exemplary embodiment of the presentinvention.

FIG. 13 is a plan view showing a lead frame according to anotherexemplary embodiment of the present invention.

FIG. 14 is a plan view showing an LED according to still anotherexemplary embodiment of the present invention.

FIG. 15 is a cross-sectional view taken along line B-B in FIG. 14.

FIGS. 16A, 16B, and 16C are perspective views showing a portion ofvarious first lead terminals applicable to an LED.

FIG. 17 is a perspective view showing a portion of a first lead terminalaccording to another exemplary embodiment of the present invention.

FIG. 18A is a plan view showing an LED according to still anotherexemplary embodiment of the present invention.

FIG. 18B is a cross-sectional view taken along line C-C in FIG. 18A.

FIG. 18C is a cross-sectional view taken along line D-D in FIG. 18A.

FIG. 19 is a plan view for showing a process of first and second leadterminals in FIGS. 18A, 18B, and 18C.

FIG. 20 is a plan view showing a process of first and second leadterminals according to another exemplary embodiment of the presentinvention.

FIG. 21A is a plan view showing an LED according to still anotherexemplary embodiment of the present invention.

FIG. 21B is a cross-sectional view taken along line C-C in FIG. 21A.

FIG. 21C is a cross-sectional view taken along line D-D in FIG. 21A.

FIG. 22A is a plan view showing an LED according to still anotherexemplary embodiment of the present invention.

FIG. 22B is a cross-sectional view taken along line C-C in FIG. 22A.

FIG. 22C is a cross-sectional view taken along line D-D in FIG. 22A.

FIG. 23 is a perspective view showing an LED according to still anotherexemplary embodiment of the present invention.

FIG. 24A is a cross-sectional view showing the LED in FIG. 23.

FIG. 24B is an enlarged view showing a portion A in FIG. 24A.

FIG. 25A is a cross-sectional view showing an LED according to stillanother exemplary embodiment of the present invention.

FIG. 25B is an enlarged view showing a portion A in FIG. 25A.

FIG. 26 is a perspective view showing an LED according to still anotherexemplary embodiment of the present invention.

FIG. 27 is a plan view showing the LED in FIG. 26.

FIG. 28 is a cross-sectional view taken along line II-II′ in FIG. 27.

FIG. 29 is a plan view showing an LED according to still anotherexemplary embodiment of the present invention.

FIG. 30 is a cross-sectional view showing the LED in FIG. 29.

FIG. 31 is an exploded perspective view showing a backlight unitaccording to an exemplary embodiment of the present invention.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

The present invention is described more fully hereinafter with referenceto the accompanying drawings, in which example embodiments of thepresent invention are shown. The present invention may, however, beembodied in many different forms and should not be construed as limitedto the example embodiments set forth herein. Rather, these exampleembodiments are provided so that this disclosure will be thorough andcomplete, and will fully convey the scope of the present invention tothose skilled in the art. In the drawings, the sizes and relative sizesof layers and regions may be exaggerated for clarity.

It will be understood that when an element or layer is referred to asbeing “on,” “connected to” or “coupled to” another element or layer, itcan be directly on, connected or coupled to the other element or layeror intervening elements or layers may be present. In contrast, when anelement is referred to as being “directly on,” “directly connected to”or “directly coupled to” another element or layer, there are nointervening elements or layers present. Like numerals refer to likeelements throughout. As used herein, the term “and/or” includes any andall combinations of one or more of the associated listed items.

It will be understood that, although the terms first, second, third etc.may be used herein to describe various elements, components, regions,layers and/or sections, these elements, components, regions, layersand/or sections should not be limited by these terms. These terms areonly used to distinguish one element, component, region, layer orsection from another region, layer or section. Thus, a first element,component, region, layer or section discussed below could be termed asecond element, component, region, layer or section without departingfrom the teachings of the present invention.

Spatially relative terms, such as “beneath,” “below,” “lower,” “above,”“upper” and the like, may be used herein for ease of description todescribe one element or feature's relationship to another element(s) orfeature(s) as illustrated in the figures. It will be understood that thespatially relative terms are intended to encompass differentorientations of the device in use or operation in addition to theorientation depicted in the figures. For example, if the device in thefigures is turned over, elements described as “below” or “beneath” otherelements or features would then be oriented “above” the other elementsor features. Thus, the exemplary term “below” can encompass both anorientation of above and below. The device may be otherwise oriented(rotated 90 degrees or at other orientations) and the spatially relativedescriptors used herein interpreted accordingly.

The terminology used herein is for the purpose of describing particularexemplary embodiments only and is not intended to be limiting of thepresent invention. As used herein, the singular forms “a,” “an” and“the” are intended to include the plural forms as well, unless thecontext clearly indicates otherwise. It will be further understood thatthe terms “comprises” and/or “comprising,” when used in thisspecification, specify the presence of stated features, integers, steps,operations, elements, and/or components, but do not preclude thepresence or addition of one or more other features, integers, steps,operations, elements, components, and/or groups thereof.

Exemplary embodiments of the invention are described herein withreference to cross-sectional illustrations that are schematicillustrations of idealized exemplary embodiments (and intermediatestructures) of the present invention. As such, variations from theshapes of the illustrations as a result, for example, of manufacturingtechniques and/or tolerances, are to be expected. Thus, exemplaryembodiments of the present invention should not be construed as limitedto the particular shapes of regions illustrated herein but are toinclude deviations in shapes that result, for example, frommanufacturing. For example, an implanted region illustrated as arectangle will, typically, have rounded or curved features and/or agradient of implant concentration at its edges rather than a binarychange from implanted to non-implanted region. Likewise, a buried regionformed by implantation may result in some implantation in the regionbetween the buried region and the surface through which the implantationtakes place. Thus, the regions illustrated in the figures are schematicin nature and their shapes are not intended to illustrate the actualshape of a region of a device and are not intended to limit the scope ofthe present invention.

Unless otherwise defined, all terms (including technical and scientificterms) used herein have the same meaning as commonly understood by oneof ordinary skill in the art to which this invention belongs. It will befurther understood that terms, such as those defined in commonly useddictionaries, should be interpreted as having a meaning that isconsistent with their meaning in the context of the relevant art andwill not be interpreted in an idealized or overly formal sense unlessexpressly so defined herein.

Hereinafter, exemplary embodiments of the present invention will beexplained in detail with reference to the accompanying drawings.

FIG. 1 is a plan view showing a light emitting diode according to anexemplary embodiment of the present invention. FIG. 2 is across-sectional view taken along line I-I′ in FIG. 1, and FIG. 3 is anenlarged view showing a lead frame in FIG. 2.

Referring to FIG. 1, FIG. 2, and FIG. 3, a light emitting diode (LED)100 according to an exemplary embodiment of the present inventionincludes a light-emitting chip 110, a metal member 120 on which thelight-emitting chip 110 is mounted, and a housing 130 combined with themetal member 120 to fix the metal member 120. Additionally, the LED 100may further include first and second conductive wires 140 and 150electrically connecting the light-emitting chip 110 to the metal member120, and an encapsulant filled in an opening portion 132 of the housing130.

In the present exemplary embodiment, the metal member 120 on which thelight-emitting chip 110 is mounted is embodied by a lead frame forapplying electric power to the light-emitting chip 110. For convenience,the same numeral will be used for the lead frame and the metal member120.

The lead frame 120 supports the light-emitting chip 110, and receiveselectric power to provide the light-emitting chip 110 with the electricpower.

The lead frame 120 may include a first lead terminal 122 and a secondlead terminal 124 spatially and electrically separated from each other.The light-emitting chip 110 is mounted on, for example, the first leadterminal 122.

The first and second lead terminals 122 and 124 may be electricallyconnected to the light-emitting chip 110 through the first and secondconducting wires 140 and 150, respectively. The first lead terminal 122may be electrically connected to the light-emitting chip 110 throughconductive adhesive. Portions of the first and second lead terminals 122and 124 are exposed out of the housing 130 to be electrically connectedto an external circuit board.

The lead frame 120 includes a base metal layer 120 a, a light-reflectinglayer 120 b formed on a surface of the base metal layer 120 a, and aprotection layer 120 c formed on a surface of the light-reflecting layer120 b as shown in FIG. 3.

The base metal layer 120 a includes metal with high electricalconductivity and processibility. For example, the base metal layer 120 aincludes copper (Cu), or copper alloy with copper (Cu) and zinc (Zn), orcopper alloy with copper (Cu) and iron (Fe). The base metal layer 120 ahas a thickness of about 0.1 mm to about 1.0 mm.

The light-reflecting layer 120 b includes metal of high lightreflectivity for enhancing light reflectivity of the lead frame 120. Forexample, the light-reflecting layer 120 b includes silver (Ag) oraluminum (Al). The light-reflecting layer 120 b may be formed on thesurface of the base metal layer 120 a through a plating method. When athickness of the light-reflecting layer 120 b increases, the lightreflectivity is improved. However, manufacturing cost may also increase.Therefore, the thickness of the light-reflecting layer 120 b isdetermined in consideration of the light reflectivity and themanufacturing cost. For example, the light-reflecting layer 120 b havinga thickness of about 1 μm to about 50 μm is formed on the surface of thebase metal layer 120 a.

The protection layer 120 c is formed on the surface of thelight-reflecting layer 120 b to protect the light-reflecting layer 120 bfrom corrosion. The light-reflecting layer 120 b formed on the basemetal layer 120 a has high light reflectivity but the light-reflectinglayer 120 b is vulnerable to moisture and heat to be easily corroded anddarkened. Therefore, in order to prevent the light-reflecting layer 120b from being corroded and darkened, the protection layer 120 c is formedon the surface of the light-reflecting layer 120 b.

The protection layer 120 c includes a diffusion barrier metal eventhough the diffusion barrier metal has a relatively lowerlight-reflectivity than the light-reflecting layer 120 b. For example,the protection layer 120 c includes gold (Au), nickel (Ni), or titanium(Ti). The protection layer 120 c including gold (Au), nickel (Ni), ortitanium (Ti) may be formed through a plating method. In detail, theprotection layer 120 c may be formed through an electrolytic platingmethod using solution providing gold (Au), nickel (Ni), or titanium (Ti)ions, or the protection layer 120 c may be formed through an electrolessplating method using a mixture of electrolytic solution providing gold(Au), nickel (Ni), or titanium (Ti) ions, a reducing agent such asdimethylaminboran (DMAB) or EDTA standard solution and an anticorrosiveagent to form gold (Au) layer, nickel (Ni) layer, or titanium (Ti)layer. Alternatively, the protection layer 120 c including gold (Au),nickel (Ni), or titanium (Ti) may be formed through a sputtering method.

When the thickness of the protection layer 120 c increases, a functionfor protecting the light-reflecting layer 120 b from chemical attack isimproved but light reflectivity is lowered to lower luminance of the LED100. On the contrary, when the thickness of the protection layer 120 cdecreases, the light reflectivity is improved but a function of theprotection layer 120 c may be deteriorated. Therefore, it is importantto determine the optimal thickness of the protection layer 120 cprotecting the light-reflecting layer 120 b, while minimizingdeterioration of the light reflectivity of the light-reflecting layer120 b.

FIG. 4 is a graph showing a relationship between a thickness of theprotection layer of gold (Au) and efficiencies of the light emittingdiode in FIG. 1. In FIG. 4, the y-axis shows an efficiency correspondingto a thickness of protection layer including gold (Au), when aconventional light-reflecting layer without the protection layer and thepackage (in detail the encapsulant 160 in FIG. 1) corresponds to anefficiency of 100%. In FIG. 4, the thickness of the light-reflectinglayer is fixed to be about 3 μm.

Referring to FIG. 3 and FIG. 4, when the thickness of the protectionlayer 120 c, which is formed on the light-reflecting layer 120 b havingabout 3 μm thickness, is substantially equal to or less than about 2 nm,the efficiency is about 90%. When the thickness of the protection layer120 c is about 200 nm, the efficiency is about 85%. When the thicknessof the protection layer 120 c is about 300 nm, the efficiency is about83%. When the thickness of the protection layer 120 c is about 600 nm,the efficiency is about 75%. When the thickness of the protection layer120 c is about 640 nm, the efficiency is about 70%, and when thethickness of the protection layer 120 c is about 700 nm, the efficiencyis about 60%. As shown in FIG. 4, the efficiency is rapidly decreasedwhen the thickness of the protection layer 120 c is over about 600 nm.Furthermore, when the thickness of the lead frame 120 arrives at 700 nm,the efficiency is dropped to be about 60% of the original efficiency.

Therefore, when the thickness of the protection layer 120 c, whichincludes gold (Au) and is formed on the light-reflecting layer 120 b, isin a range of about 0.1 nm, which is the minimum thickness of theprotection layer 120 c capable of protecting the light-reflecting layer120 b, to about 600 nm, which is maximum thickness of the protectionlayer 120 c capable of maintaining the efficiency more than about aspecific level, the efficiency of the LED 100 is over about 75%.

FIG. 5 is a graph showing a relationship between a thickness of theprotection layer of nickel (Ni) and titanium (Ti), and lighttransmittances.

Referring to FIG. 3 and FIG. 5, light passing through the protectionlayer 120 c is reflected by the light-reflecting layer 120 b havingrelatively high light reflectivity. Therefore, when light transmittanceof the protection layer 120 c becomes higher, the light reflectivity ofthe lead frame 120 becomes higher. When the thickness of the nickel (Ni)layer or titanium (Ti) layer operating as the protection layer 120 cincreases, the light transmittance decreases. However, even when thethickness of nickel (Ni) layer or titanium (Ti) layer is about 20 nm,the light transmittance is over about 10%. As the thickness of theprotection layer 120 c increases, the light reflectivity of the leadframe 120 decreases but function of the protection layer 120 c becomesbetter. Therefore, the reflectivity of the lead frame 120 becomes betterin comparison with the light-reflecting layer 120 b, on which noprotection layer is formed to be corroded and darkened.

In other words, when the thickness of the protection layer 120 c, whichincludes nickel (Ni) and titanium (Ti) and is formed on thelight-reflecting layer 120 b, is in a range of about 0.1 nm which is theminimum thickness of the protection layer 120 c capable of protectingthe light-reflecting layer 120 b, to about 20 nm which is maximumthickness of the protection layer 120 c capable of maintaining theefficiency more than about a specific level, the light-reflecting layer120 b is prevented from being corroded and darkened while maintainingthe light reflectivity of the lead frame 120.

The light-reflecting layer 120 b and the protection layer 120 c may beformed on both of the upper and lower surfaces of the lead frame 120.Alternatively, the light-reflecting layer 120 b and the protection layer120 c may be formed on one of the upper and lower surfaces of the leadframe 120, or portions of the lead frame 120, on which thelight-reflecting layer 120 b and the protection layer 120 c are requiredto be formed.

FIG. 6 is a cross-sectional view showing a lead frame according toanother exemplary embodiment of the present invention. The lead frame inFIG. 6 is substantially the same as the lead frame in FIG. 3, except fora nickel layer. Thus, same reference numerals will be used for the sameelements, and any further explanation will be omitted.

Referring to FIG. 6, a lead frame 120 may further include a nickel layer120 d disposed between the base metal layer 120 a and thelight-reflecting layer 120 b. As shown in FIG. 6, when the nickel layer120 d is formed on base metal layer 120 a, the light-reflecting layer120 b is formed on the nickel layer 120 d, and the protection layer 120c is formed on the light-reflecting layer 120 b, the same lightreflectivity may be obtained as shown in FIG. 3. When the nickel layer120 d which may have a lower price than silver (Ag), is firstly formedbefore the light-reflecting layer 120 b including silver (Ag), athickness of the light-reflecting layer 120 b may be reduced to lower amanufacturing cost.

Referring again to FIG. 1 and FIG. 2, the light-emitting chip 110 ismounted on the lead frame 120, and the light-emitting chip 110 generateslight when the light-emitting chip 110 receives electric power throughthe lead frame 120. For example, the light-emitting chip 110 is mountedon the first lead terminal 122, and the light-emitting chip 110 iselectrically connected to the first and second lead terminals 122 and124 through the first and second conducting wires 140 and 150,respectively. The light-emitting chip 110 includes a semiconductor suchas, for example, gallium nitride (GaN), gallium arsenic nitride (GaAsN),or indium nitride (IN), etc. The light-emitting chip 110 may employsemiconductor materials according to wavelength of light. For example,the light-emitting chip 110 emits blue ultraviolet light, light, greenlight, red light, or yellow light.

The housing 130 is combined with the lead frame 120 to fix the leadframe 120. In detail, the housing 130 enwraps at least portions of thefirst and second lead terminals 122 and 124 to fix a position of thefirst and second lead terminals 122 and 124. The housing 130 includes,for example, polyphthalamide (PPA) resin, etc.

The housing 130 includes an opening portion 132 exposing thelight-emitting chip 110 and a portion of the lead frame 120, on whichthe light-emitting chip 110 is mounted. The opening portion 132 mayhave, for example, an inverted truncated cone shape. In other words, theopening portion 132 may have a shape of which size increases along adirection from a lower portion adjacent to the lead frame 120 to anupper portion. Therefore, an inner side of the housing 130, whichcorresponds to the opening portion 132, is inclined, and the inner sideof the housing 130 may have a light reflecting layer formed thereon.

The encapsulant 160 is filled in the opening portion 132 of the housing130 to encapsulate the light-emitting chip 110. The encapsulant 160protects the light-emitting chip 110. The encapsulant 160 includes, forexample, optically transparent epoxy or silicone (or silicon resin). Theencapsulant 160 may include fluorescent particles 162 distributedtherein to change wavelength of light emitted by the light-emitting chip110. For example, the encapsulant 160 includes, at least of red, green,and blue fluorescent particles to generate required colored light suchas white light.

The LED 100 may emit white light through the light-emitting chip 110 andthe fluorescent particles 162.

For example, the light-emitting chip 110 may emit blue light, and thefluorescent particles 162 may be yellow fluorescent particles changingportions of the blue light into yellow light to generate white light. Indetail, the blue light generated by the light-emitting chip 110 may havea wavelength in a range of about 430 nm to about 470 nm, and thelight-emitting chip 110 may include an InGaN semiconductor. The yellowfluorescent particles receive the blue light to emit yellow light. Theyellow fluorescent particles may include, for example, yttrium aluminumgarnet (Y₃Al₅O₁₂; or YAG) series, silicate series, and TAG series.Therefore, the LED 100 may generate white light in which the blue lightemitted by the light-emitting chip 110 and the yellow light emitted bythe yellow fluorescent particles mixed with each other.

Alternatively, the light-emitting chip 110 may generate blue light, andthe fluorescent particles 162 may include red fluorescent particlesconverting blue light into red light, and green fluorescent particlesconverting blue light into green light. The red fluorescent particlesmay include, for example, inorganic substances having similar crystalstructure to that of SrS:Eu, (Sr,Ca)S:Eu, CaS:Eu, (Sr,Ca)GeS:Eu andCaAlSiN₃, or solid solution. The green fluorescent particles mayinclude, for example, SrGa₂S₄:Eu and (Ba,Sr,Ca)₂SiO₄:Eu, etc. Therefore,the LED 100 may generate white light in which the blue light generatedby the light-emitting chip 110, the red light emitted by the redfluorescent particles, and the green light emitted by the greenfluorescent particles are mixed with each other. As described above,when white color is generated by using the light-emitting chip 110emitting blue light, the red fluorescent particles and the greenfluorescent particles, the color reproducibility is enhanced to be in arange of about 90% to about 110%, which is about 20% improved incomparison with the white color generated by using the light-emittingchip 110 emitting blue light and yellow fluorescent particles, of whichcolor reproducibility is about 85%.

Alternatively, the LED 100 may include two light-emitting chips 110emitting different colored light and one kind of fluorescent particles162. For example, the two light-emitting chips 110 may emit blue lightand red light, respectively, and the fluorescent particles 162 may begreen fluorescent particles converting the blue light emitted by theblue light-emitting chip into green light. Alternatively, the twolight-emitting chips 110 may emit blue light and green light,respectively, and the fluorescent particles 162 may be red fluorescentparticles converting the blue light or green light emitted by the bluelight-emitting chip into red light.

According to the LED 100 having a structure described above, lightemitted by the light-emitting chip 110 or the fluorescent particles 162and advancing downward is reflected by the lead frame 120 to advanceupward. In this case, by using the lead frame 120 including thelight-reflecting layer 120 b including silver (Ag) or aluminum (Al), andthe protection layer 120 c including gold (Au), nickel (Ni), or titanium(Ti) and formed on the light-reflecting layer 120 b, the lightreflectivity may be maintained to be over a specific level whilepreventing being corroded and darkened.

The lead frame 120 may be applied to various models, for example such asa top-view package, a side-view package, a lamp type package, a chiptype package, etc.

FIG. 7 is a cross-sectional view showing an LED according to anotherexemplary embodiment of the present invention.

Referring to FIG. 7, an LED 200 according to another exemplaryembodiment of the present invention includes a light-emitting chip 110,a metal member 220 on which the light-emitting chip 110 is mounted, leadframes 120 and 122 applying electric power to the light-emitting chip110, and a housing 130 fixing the metal member 220 and the lead frame120. The LED 200 may further include first and second conducting wires140 and 150 electrically connecting the light-emitting chip 110 to thelead frame 120, and an encapsulant 160 encapsulating the light-emittingchip 110.

According to the present exemplary embodiment, the metal member 220, onwhich the light-emitting chip 110 is mounted, is a slug radiating heatgenerated by the light-emitting chip 110. For convenience, the samenumeral will be used for the slug and the metal member 220. Furthermore,other elements except the slug 220 are substantially the same as theelements in FIG. 1 and FIG. 2. Thus, same reference numbers will be usedfor the same elements and any further explanation will be omitted.

The slug 220 is disposed at a center portion of the housing 130, and thelight-emitting chip 110 is mounted on an upper portion of the slug 220.The lower portion of the slug 220 is exposed out of the housing 130 toenhance efficiency of heat radiation.

The slug 220 includes a base metal layer 120 a, a light-reflecting layer120 b formed on the base metal layer 120 a, and a protection layer 120 cformed on the light-reflecting layer 120 b to prevent thelight-reflecting layer 120 b from being corroded and darkened whilemaintaining high light reflectivity, substantially the same as the leadframe 120 in FIG. 3. For example, the light-reflecting layer 120 b mayinclude silver (Ag) or aluminum (Al), and the protection layer 120 c mayinclude gold (Au), nickel (Ni), or titanium (Ti). The slug 220 issubstantially the same as the lead frame 120 in FIG. 3 except for ashape. Thus, any further explanation will be omitted.

FIG. 8 is a plan view showing a portion of an LED according to stillanother exemplary embodiment of the present invention. FIG. 9 is across-sectional view taken along line A-A′ in FIG. 8, FIG. 10 is across-sectional view taken along line B-B′ in FIG. 8, and FIG. 11 is across-sectional view taken along line C-C′ in FIG. 8.

Referring to FIG. 8, FIG. 9, FIG. 10, and FIG. 11, an LED according tostill another exemplary embodiment of the present invention includes alead frame having a first lead terminal 21 and a second lead terminal23. As shown in FIG. 3, the first and second lead terminals 21 and 23may include, for example, a base metal layer, a light-reflecting layerincluding silver (Ag) or aluminum (Al) and formed on the base metallayer, and a protection layer including gold (Au), nickel (Ti), ortitanium (Ti) and formed on the light-reflecting layer.

The first lead terminal 21 includes a chip-mounting portion 21 a onwhich the light-emitting chip 27 is mounted, a first external leadportion 21 b extended from the chip-mounting portion 21 a to be disposedout of the housing 25, and a first wing portion 21 c extended from thechip-mounting portion 21 a. The second lead terminal 23 includes a wirebonding portion 23 a, a second external lead portion 23 b extended fromthe wire bonding portion 23 a to be disposed out of the housing 25, anda second wing portion 23 c extended from the wire bonding portion 23 a.The first and second lead terminals 21 and 23 are spatially andelectrically separated from each other. The first and second wingportions 21 c and 23 c are bent from the chip-mounting portion 21 a andthe wire bonding portion 23 a, respectively to form a light-reflectingsurface. The first and second wing portions 21 c and 23 c are disposedopposite to each other with respect to the chip-mounting portion 21 aand in parallel with each other.

The first wing portion 21 c may be extended to be disposed adjacent to aside of the wire bonding portion 23 c of the second lead terminal 23.The first wing portion 21 c may have a wider width than that of thesecond wing portion 23 c as shown in FIG. 8, but the first wing portion21 c may have an equal width to the width of the second wing portion 23c or narrower width than that of the second wing portion 23 c. Forexample, the second wing portion 23 c may be extended to a portion ofthe first lead terminal 21, in which the chip-mounting portion 21 a isconnected to the first external lead portion 21 b, so that the secondwing portion 23 c may have equal width to that of the first wing portion21 c or wider width than that of the first wing portion 21 c.

The first and second wing portions 21 c and 23 c are bent from thechip-mounting portion 21 a and the wire bonding portion 23 a,respectively. The light-reflecting surface defined by the first andsecond wing portions 21 c and 23 c may be inclined with respect to thechip-mounting portion 21 a or perpendicular to the chip-mounting portion21 a. The first and second wing portions 21 c and 23 c may be bent.Alternatively, the first and second wing portions 21 c and 23 c may beformed through various methods, for example, such as a press method, awelding method, etc.

The housing 25 is combined with the first and second lead terminals 21and 23 to support the first and second lead terminals 21 and 23. Thehousing 25 may be formed through a molding method. In detail, the firstand second lead terminals 21 and 23 are inserted in a molding cast andmolding resin is injected into the molding cast to form the housing 25.The housing 25 encapsulates lower surfaces of the chip-mounting portion21 a and the wire bonding portion 23 a. Additionally, the housing 25 mayencapsulate outer surfaces of the first and second wing portions 21 cand 23 c. The outer surfaces of the first and second wing portions 21 cand 23 c may be entirely encapsulated by the housing 25. Alternatively,at least a portion of the outer surfaces of the first and second wingportions 21 c and 23 c may be exposed to an outside.

The housing 25 defines inner walls of the opening portion together withthe first and second wing portions 21 c and 23 c. Especially, thehousing 25 defines an inner wall 25 w of the opening portion, which issubstantially perpendicular to the light-reflecting surface defined bythe first and second wing portions 21 c and 23 c. The inner wall 25 wmay be inclined. The chip-mounting portion 21 a and the wire bondingportion 23 a define a bottom surface of the opening portion.

The first and second lead terminals 21 and 23 include first and secondexternal lead portions 21 b and 23 b exposed out of the housing 25 to beelectrically connected to an external power source. The first and secondexternal lead portions 21 b and 23 b may have various shapes and be bentto have various shapes.

The light-emitting chip 27 is mounted on the chip-mounting portion 21 aof the first lead terminal 21, and electrically connected to the wirebonding portion 23 a of the second lead terminal 23 through the firstconducting wire 29 a. Alternatively, the light-emitting chip 27 may beelectrically connected to the first lead terminal 21 through the secondconducting wire 29 b or a conductive adhesive.

An encapsulant (not shown) including fluorescent particles distributedtherein may be filled in the opening of the housing 25 to encapsulatethe light-emitting chip 27. The encapsulant including fluorescentparticles distributed therein was explained above in reference to FIG.2. Thus, any further explanation will be omitted.

According to the present exemplary embodiment, the first wing portion 21c of the first lead terminal 21 and the second wing portion 23 c ofsecond lead terminal 23 define two inner walls of the opening portion,so that light reflectivity of the opening portion inner wall may beimproved. Especially, in a side-view type LED having a linear openingportion, the first and second wing portions 21 c and 23 c are disposedalong a major axis direction of the opening portion, so that an area ofthe light-reflecting surface defined by the first and second wingportions 21 c and 23 c may be increased. Furthermore, the first andsecond wing portions 21 c and 23 c reflect light advancing the housing25 to prevent the housing 25 from discoloration. Additionally, heattransferred to the second wing portion 23 c may be radiated through thesecond lead terminal 23. Therefore, heat radiation capacity of the LEDmay be improved since the second lead terminal 23 also radiates heatsubstantially the same as the first lead terminal 21.

FIG. 12 is a plan view for showing a process of making first and secondlead terminals according to an exemplary embodiment of the presentinvention.

Referring to FIG. 12, a first lead terminal 21 and a second leadterminal 23 are formed by punching a flat metal plate. The first leadterminal 21 includes a chip-mounting portion 21 a, a first external leadportion 21 b and a first wing portion 21 c. The first wing portion 21 cis upwardly bent along a dotted line B to define a firstlight-reflecting surface. The second lead terminal 23 includes a wirebonding portion 23 a, a second external lead portion 23 b, and a secondwing portion 23 c. The second wing portion 23 c is upwardly bent along adotted line B to define a second light-reflecting surface. The firstwing portion 21 c may be extended along a side of the wire bondingportion 23 a of the second lead terminal 23. The second wing portion 23c is terminated at a region adjacent to the chip-mounting portion 21 a.However, the second wing portion 23 c may be extended to a region inwhich the chip-mounting portion 21 a is connected with the firstexternal lead portion 21 b.

The first and second lead terminals 21 and 23 may be formed through acasting method or a welding method. When the first and second leadterminals 21 and 23 are formed through a casting method or a weldingmethod, an enfolding process of the first and second wing portions 21 cand 23 c may be omitted.

According to the present exemplary embodiment, the first and second leadterminals 21 and 23 have the first and second wing portions 21 c and 23c with a rectangular shape, respectively. However, the shapes of thefirst and second wing portions 21 c and 23 c are not limited to therectangular shape. That is, the shapes of the first and second wingportions 21 c and 23 c may be variously adjusted according to a shape ofa package of an LED.

FIG. 13 is a plan view showing a lead frame according to anotherexemplary embodiment of the present invention.

Referring to FIG. 13, a first lead terminal 31 includes a chip-mountingportion 31 a, a first external lead portion 31 b, and a first wingportion 31 c, and a second lead terminal 33 includes a wire bondingportion 33 a, a second external lead portion 33 b, and a second wingportion 33 c. The first and second wing portions 31 c and 33 c have awidth increasing in a direction far away from the chip-mounting portion31 a and the wire bonding portion 33 a, respectively. When the innerwalls 25 w of the opening portion are inclined as shown in FIG. 9, thefirst and second wing portions 31 c and 33 c have the increasing widthto correspond to the shape of the inner walls 25 w, so that the area ofthe light-reflecting surface is increased.

In the present exemplary embodiment, a side-view type LED having alinear opening portion is disclosed and explained. However, the presentexemplary embodiment is not limited to the side-view type LED having alinear opening portion. The present exemplary embodiment may be appliedto various packages employing a lead frame, a plastic housing, andhaving circular, rectangular opening portion, etc.

FIG. 14 is a plan view showing an LED according to still anotherexemplary embodiment of the present invention, and FIG. 15 is across-sectional view taken along line B-B in FIG. 14. FIG. 16A, FIG.16B, and FIG. 16C are perspective views showing a portion of variousfirst lead terminals applicable to an LED. FIG. 17 is a perspective viewshowing a portion of a first lead terminal according to anotherexemplary embodiment of the present invention.

Referring to FIG. 14 and FIG. 15, an LED includes a first lead terminal51 and a second lead terminal 53. The first and second lead terminals 51and 53 include a base metal layer, a light-reflecting layer includingsilver (Ag) or aluminum (Al), and gold (Au), and a protection layerincluding gold (Au), nickel (Ni), or titanium (Ti), as shown in FIG. 3.

The first lead terminal 51 includes a chip-mounting portion 51 b onwhich a light-emitting chip 57 is mounted, a step portion 51 a disposedto be lower than the chip-mounting portion 51 b, and a first inclinedportion 51 c disposed between the chip-mounting portion 51 b and thestep portion 51 a to define a light-reflecting surface (see FIG. 16A).The second lead terminal 53 is spaced apart from the first lead terminal51. The second lead terminal 53 may be disposed at the same height asthe step portion 51 a of the first lead terminal 51.

The first lead terminal 51 may further include a second inclined portion51 d connected to the chip-mounting portion 51 b to be disposed oppositeto the first inclined portion 51 c (see FIG. 16B). Additionally, thefirst lead terminal 51 may further include an end portion 51 e extendedfrom the second inclined portion 51 d to be disposed at the same heightas the step portion 51 a (see FIG. 16C).

The first and second lead terminals 51 and 53 are supported by thehousing 55. For convenience, the housing 55 is divided into an upperhousing 55 a and a lower housing 55 b, which are disposed upper andlower portions with respect to the step portion 51 a of the first leadterminal 51 and the second lead terminal 53.

The housing 55 may have an opening portion 56 exposing portions of thefirst and second lead terminals 51 and 53. The opening portion 56exposes the chip-mounting portion 51 b of the first lead terminal 51,the first and second inclined portions 51 c and 51 d, and a portion ofthe second lead terminal 53. Furthermore, the opening portion 56 mayexpose a portion of the step portion 51 a of the first lead terminal 51.

The first and second lead terminals 51 and 53 are spaced apart from eachother in the opening portion 56. The first and second lead terminals 51and 53 are extended out of the housing 55 in order to be electricallyconnected to an external power source. The first and second leadterminals 51 and 53 extended out of the housing 55 may have variousshapes and be bent variously.

The chip-mounting portion 51 b of the first lead terminal 51 is disposedclose to the lower housing 55 b, so that a recessed portion is formed ata bottom surface of the opening portion 56. The first inclined portion51 c of the first lead terminal 51 crosses over a major axis directionof the opening portion 56. The first inclined portion 51 c of the firstlead terminal 51 may make contact with the inner wall of a minor axisdirection of the housing 55 or be terminated before meeting the innerwall. That is, the first inclined portion 51 c exposed through theopening portion 56 is not continuous but intermittent. Therefore, thelight reflectivity of the major axis direction is improved withoutchanging directivity of the minor axis direction, and it is possible toseparately control light distribution of the major axis direction andthe minor axis direction. Also, the second inclined portion 51 d of thefirst lead terminal 51 crosses over the major axis direction of theopening portion 56. The second inclined portion 51 d of the first leadterminal 51 may make contact with the inner wall of a minor axisdirection of the housing 55 or be terminated before meeting the innerwall. The second inclined portion 51 d is symmetric with first inclinedportion 51 c, so that light distribution becomes symmetric.

The light-emitting chip 57 is mounted on the chip-mounting portion 51 b,and electrically connected to the second lead terminal 53 through theconducting wire 59. Light generated by the light-emitting chip 57 isreflected by the first and second inclined portions 51 c and 51 d,before arriving at the inner wall 55 w of the housing 55. Therefore,efficiency of the LED is improved, since a portion of the lightgenerated by the light-emitting chip 57 is reflected by the first andsecond inclined portion 51 c and 51 d of light reflectivity.Additionally, an amount of light advancing toward the inner wall of thehousing 55 is decreased to reduce discoloration of the inner wall of thehousing 55, so that a life span of the LED is improved.

Referring to FIG. 17, in order to improve the light reflectivity of theminor axis direction and prevent discoloration of the inner wall of thehousing 55 in the minor axis, the first lead terminal 51 may furtherinclude wing portions 51 f extended from the chip-mounting portion 51 balong the minor axis direction of the opening portion 56. The wingportions 51 f connected with the chip-mounting portion 51 b is bent toform third and fourth inclined portions. Additionally, the wing portions51 f are separated from the first and second inclined portions 51 c and51 d, so that the wing portions 51 f may be bent to have different anglefrom that of the first and second inclined portions 51 c and 51 d.Therefore, reflectivity of the minor axis direction and reflectivity ofthe major axis direction may be separately controlled.

The encapsulant 63 including fluorescent particles distributed thereinmay be formed to encapsulate the light-emitting chip 57. The encapsulant63 may be formed through dropping liquid resin including the fluorescentparticles distributed therein onto the recessed portion of thechip-mounting portion 51 b. Therefore, the encapsulant 63 confined inthe recessed portion to have a convex shape is formed. The encapsulant63 including fluorescent particles distributed therein was explainedabove in reference to FIG. 2. Thus, any further explanation will beomitted.

The encapsulant 63 may fill up with the opening portion 56.Alternatively, the encapsulant 63 may be confined only in the recessedportion, and the opening portion 56 may be filled up with a transparentmolding part 65.

FIG. 18A is a plan view showing an LED according to still anotherexemplary embodiment of the present invention. FIG. 18B is across-sectional view taken along line C-C in FIG. 18A, and FIG. 18C is across-sectional view taken along line D-D in FIG. 18A. In FIG. 18C, wingportions are expressed with a dotted line.

Referring to FIGS. 18A, FIG. 18B, and FIG. 18C, an LED according to thepresent exemplary embodiment includes a first lead terminal 71 and asecond lead terminal 73.

The first and second lead terminals 71 and 73 include a base metallayer, a light-reflecting layer including silver (Ag) or aluminum (Al),and a protection layer including gold (Au), nickel (Ni) or titanium(Ti), as shown in FIG. 3.

The first lead terminal 71 includes a chip-mounting portion 71 a onwhich a light-emitting chip 77 is mounted, and a first wing portions 71w upwardly extended from the chip-mounting portion 71 a to define alight-reflecting surface. The second lead terminal 73 may include a wirebonding portion 73 a, and a second wing portions 73 w upwardly extendedfrom the wire bonding portion 73 a to define a light-reflecting surface.The first and second lead terminals 71 and 73 are spaced apart from eachother, and the first and second wing portions 71 w and 73 w are disposedparallel with each other to define light-reflecting surfaces. The firstand second wing portions 71 w and 73 w may be symmetric with respect tothe chip-mounting portion 71 a and the wire bonding portion 73 a toobtain symmetrical light distribution. However, the first and secondwing portions 71 w and 73 w have different widths than each other andare asymmetric.

The housing 75 is combined with the first and second lead terminals 71and 73 to support the first and second lead terminals 71 and 73. Thehousing 75 covers a lower surface of the first and second lead terminals71 and 73, and encapsulates outer surfaces of the first and second wingportions 71 w and 73 w. The housing 75 may fill up with a space betweenthe chip-mounting portion 71 a of the first lead terminal 71 and thewire bonding portion 73 a of the second lead terminal 73, and a spacebetween the first and second wing portions 71 w and 73 w. Additionally,the housing 75 may cover the upper surface of the first and second wingportions 71 w and 73 w.

The first and second lead terminals 71 and 73 are extended out of thehousing 75 to be electrically connected to an external power source. Thefirst and second lead terminals 71 and 73 may have various shapes, andmay be bent in various ways.

The first and second wing portions 71 w and 73 w are disposed parallelwith each other to define the light-reflecting surface, and the housing75 may have an inner wall defining an opening portion with the first andsecond wing portions 71 w and 73 w. The housing 75 has inner walls 75 wconnecting the light-reflecting surface defined by the first and secondwing portions 71 w and 73 w. The inner walls 75 w may be inclined.

The light-emitting chip 77 is mounted on the chip-mounting portion 71 aof the first lead terminal 71, and electrically connected to the secondlead terminal 73 through the conducting wire 79. The light-emitting chip77 may be electrically connected to the first lead terminal 71 and thesecond lead terminal 73 through two conducting wires 79, respectively.Alternatively, the light-emitting chip 77 may be electrically connectedto the first lead terminal 71 through a conductive adhesive, and to thesecond lead terminal 73 through one conducting wire 79.

According to the present exemplary embodiment, the first and second leadterminals 71 and 73 are disposed at the bottom surface and both sidesurfaces of the opening portion, so that reflectivity of light generatedby the light-emitting chip 77 may be improved. Especially, in aside-view type LED having a linear shaped opening portion, the first andsecond wing portions 71 w and 73 w are disposed along a major axisdirection of the opening portion, so that an area of thelight-reflecting surface may be increased. The first and second wingportions 71 w and 73 w reflect light advancing toward the housing 75 todecrease discoloration of the housing 75. Additionally, the first andsecond wing portions 71 w and 73 w radiate heat to improve heatradiating capacitance of the package. Furthermore, when the thickness ofthe housing 75 surrounding the outer surface of the first and secondwing portions 71 w and 73 w is reduced, the housing 75 radiates heatmore easily to improve heat-radiating ability.

FIG. 19 is a plan view for showing a process of first and second leadterminals in FIGS. 18A, FIG. 18B, and FIG. 18C, and FIG. 20 is a planview showing a process of first and second lead terminals according toanother exemplary embodiment of the present invention.

Referring to FIG. 19, a first lead terminal 71 and a second leadterminal 73 are formed by punching or pressing a flat metal plate. Thefirst lead terminal 71 includes a chip-mounting portion 71 a and a firstwing portion 71 w extended from the chip-mounting portion 71 a, and thesecond lead terminal 73 includes a wire bonding portion 73 a and asecond wing portion 73 w extended from the wire bonding portion 73 a.The first and second wing portions 71 w and 73 w are bent upward todefine light-reflecting surfaces.

According to the present exemplary embodiment, the first and second leadterminals 71 and 73 have the first and second wing portions 71 w and 73w with rectangular shape, but the shapes of the first and second wingportions 71 w and 73 w are not limited to the rectangular shape.

Referring to FIG. 20, a first lead terminal 81 includes a chip-mountingportion 81 a and a first wing portion 81 w connected to thechip-mounting portion 81 a, and a second lead terminal 83 includes awire bonding portion 83 a and a second wing portion 83 w connected tothe wire bonding portion 83 a. The first and second wing portions 81 wand 83 w have a width increasing in a direction far away from thechip-mounting portion 81 a and the wire bonding portion 83 a,respectively. The first and second wing portions 81 w and 83 w having anincreasing width corresponding to the inner walls 75 w that areinclined. For example, when the inner walls 75 w are inclined as shownin FIG. 18, an area of the light-reflecting surface increases along alongitudinal direction.

FIG. 21A is a plan view showing an LED according to still anotherexemplary embodiment of the present invention. FIG. 21B is across-sectional view taken along line C-C in FIG. 21A, and FIG. 21C is across-sectional view taken along line D-D in FIG. 21A. In FIG. 21C, awing portions is expressed with a dotted line. For convenience, alight-emitting chip and a conducting wire are omitted.

Referring to FIG. 21A, FIG. 21B, and FIG. 21C, an LED according to thepresent exemplary embodiment is substantially same as the LED in FIG.18, except that an outer surface of first and second wing portions 71 wand 73 w are exposed out of the housing 85. That is, at least a portionof the outer surfaces of the first and second wing portions 71 w and 73w is exposed. Therefore, heat generated from the LED may be easilyradiated through the first and second wing portions 71 w and 73 w.

FIG. 22A is a plan view showing an LED according to still anotherexemplary embodiment of the present invention. FIG. 22B is across-sectional view taken along line C-C in FIG. 22A, and FIG. 22C is across-sectional view taken along line D-D in FIG. 22A. In FIG. 22C, awing portions are expressed with a dotted line. For convenience, alight-emitting chip and a conducting wire are omitted.

Referring to FIG. 22A, FIG. 22B, and FIG. 22C, an LED according to thepresent exemplary embodiment is substantially same as the LED in FIG. 18except that a chip-mounting portion 91 a of a first lead terminal 91, awire bonding portion 93 a of a second lead terminal 93, a first wingportion 91 w and a second wing portions 93 w are longer thancorresponding elements in FIG. 18, and the first and second wingportions 91 w and 93 w occupy major portions of the side portion of thepackage. The housing 95 covers lower surfaces of the first and secondlead terminals 91 and 93, and fills up with a space between the firstand second lead terminals 91 and 93 to combine the first and second leadterminals 91 and 93. Additionally, the housing 95 has inner walls 95 wconnecting end portions of the first and second wing portions 91 w and93 w operating as the light-reflecting surface. The inner walls 95 w maybe formed to be inclined.

According to the present exemplary embodiment, the width of the firstand second wing portions 91 w and 93 w is increased to correspond to thewidth of the housing 95, so that heat radiation may be improved.

In the previous exemplary embodiments, a side-view type LED of which apackage including a linear shaped opening portion was explained.However, the present exemplary embodiment is not limited to the aboveside-view type LED. The present exemplary embodiment may be applied tovarious type LEDs having a plastic housing, circular or rectangularopening portions, etc.

FIG. 23 is a perspective view showing an LED according to still anotherexemplary embodiment of the present invention. FIG. 24A is across-sectional view showing the LED in FIG. 23, and FIG. 24B is anenlarged view showing a portion A in FIG. 24A.

Referring to FIG. 23, FIG. 24A, and FIG. 24B, an LED according to thepresent exemplary embodiment includes a light-emitting chip 2, firstlead and second lead terminals 12 and 14 applying electric power to thelight-emitting chip 2, a housing 20 supporting the first and second leadterminals 12 and 14, and an encapsulant 30 which is opticallytransparent and protects the light-emitting chip 2.

The first and second lead terminals 12 and 14 include a base metallayer, a light-reflecting layer including silver (Ag) or aluminum (Al),and a protection layer including gold (Au), nickel (Ni), or titanium(Ti), as shown in FIG. 3.

The first and second lead terminals 12 and 14 have a plate-shape. Thefirst and second lead terminals 12 and 14 are supported by the housing30 in a state of being spaced apart from each other. The first andsecond lead terminals 12 and 14 include recessed portions 122 and 142recessed to have the same depth. The recessed portion 122 of the firstlead terminal 12 and the recessed portion 142 of the second leadterminals 14 form a cup on which the light-emitting chip 2 is mounted. Afirst gap between the first and second lead terminals 12 and 14, whichis disposed at an outside of the cup, is greater than a second gapbetween the first and second lead terminals 12 and 14, which is disposedat inside of the gap, so that the housing 20 supports the first andsecond lead terminals 12 and 14 more tightly to improve durability.

The housing 20 covers portions of the first and second lead terminals 12and 14, except for a bottom surface of the cup defined by the recessedportions 122 and 142. The bottom surfaces of the recessed portions 122and 142, or the bottom surfaces 123 and 143 of the cup are exposed to anoutside. Preferably, the bottom surfaces 123 and 143 of the cup aredisposed in the same plane as the bottom surface of the housing 20. Inthis case, the bottom surfaces 123 and 143 of the cup may beelectrically connected to an external printed circuit board to applyelectric power to the light-emitting chip 2. The bottom surfaces 123 and143 of the cup have a relatively thin thickness and large area and areexposed to improve heat radiation of the light-emitting chip 2.

The first and second lead terminals 12 and 14 include wing portions 124and 144 extended from the recessed portions 122 and 142 to be disposedout of the housing 20, respectively. The wing portions 124 and 144operate as a heat-radiating portion radiating heat generated by thelight-emitting chip 2. The wing portions 124 and 144 have relatively alarge area and are exposed to effectively radiate heat generated by thelight-emitting chip 2. The wing portions 124 and 144 may be electricallyconnected to an external printed circuit board to apply electric powerto the light-emitting chip 2. In this case, the bottom surface 123 and143 of the cup radiates heat only.

The light-emitting chip 2 is mounted on the recessed portion 122 of thefirst lead terminal 12 and electrically connected to the first leadterminal 12. The light-emitting chip 2 is electrically connected to therecessed portion 142 of the second lead terminal 14 through a conductingwire.

The first and second lead terminals 12 and 14 include inclined portionsconnecting the bottom surface of the recessed portions 122 and 142 (orbottom surfaces 123 and 143 of the cup) to the wing portions 124 and144. The inclined portions are flat with respect to the recessedportions 122 and 142 to reflect a portion of light emitted by thelight-emitting chip 2 upward.

The first and second lead terminals 12 and 14 may have a rough surface Ras shown in FIG. 24B. The rough surface R may be formed through asurface processing technology, for example, such as a sand blastingmethod. The rough surface R of the recessed portion 122 and 142 diffuseslight to broaden directivity of light and improve efficiency of light.The rough surface R of the first and second lead terminals 12 and 14,which is disposed outside of the recessed portion 122 and 142 andcovered by the housing 20, improves adhesive force between the housing20 and the first and second lead terminals 12 and 14.

The cup defined by the recessed portions 122 and 142 may be filled upwith an encapsulant 30 including optically transparent resin. Forexample, the encapsulant 30 may include a first encapsulating part 32including silicone (or silicon resin), and a second encapsulating part34 including epoxy resin or hard silicone (or silicon resin). At leastone of the first and second encapsulating parts 32 and 34 may includefluorescent particles distributed therein.

FIG. 25A is a cross-sectional view showing an LED according to stillanother exemplary embodiment of the present invention, and FIG. 25B isan enlarged view showing a portion A in FIG. 25A. An LED according tothe present exemplary embodiment has substantially the same elements asthe LED in FIG. 24 except vertical portions. Thus, the same referencenumerals will be used to refer to the same elements in FIG. 24A and FIG.24B, and any further explanation will be omitted.

Referring to FIG. 25A and FIG. 25B, the first and second lead terminals12 and 14 include recessed portions 122 and 142 (or bottom surfaces 123and 143 of a cup), vertical portions vertically extended from therecessed portions 122 and 142 to define a base portion 5 of the cup,inclined portions extended from the vertical portions to define an upperportion 6 of the cup, and wing portions 124 and 144 extended from theinclined portions.

Therefore, the cup includes the base portion 5 defined by the verticalportions and the recessed portions 122 and 142, and the upper portionsdefined by the inclined portions. The base portion 5 may make it easierto form a first encapsulating part 32.

FIG. 26 is a perspective view showing an LED according to still anotherexemplary embodiment of the present invention. FIG. 27 is a plan viewshowing the LED in FIG. 26, and FIG. 28 is a cross-sectional view takenalong line II-IF in FIG. 27.

Referring to FIG. 26, FIG. 27, and FIG. 28, an LED includes alight-emitting chip 2, a housing 10, a lead frame 20, an encapsulant 30,and a reflector 40.

The lead frame 20 may include six lead terminals 22 and 24. The six leadterminals 22 and 24 are supported by the housing 10. The lead frame 20includes a base metal layer, a light-reflecting layer including silver(Ag) or aluminum (Al), and a protection layer including gold (Au),nickel (Ni), or titanium (Ti) as shown in FIG. 3.

The housing 10 is formed through a molding method using resin, and acenter of an upper portion of the housing 10 has an opening portion 12in which the light-emitting chip 2 is disposed. The housing 10 dividessix lead terminals 22 and 24 into inner lead terminal 22 a and 24 adisposed inside of an opening portion 12, and outer lead terminal 22 band 24 b disposed outside of the opening portion 12. The number of thelead terminals 22 and 24 of the lead frame 20 may be variously adjusted.

A light-emitting chip 2 is electrically connected to three leadterminals 22 of the lead frame 20 in a direct method, and threeremaining lead terminals 24 through conductive wires.

The reflector 40 is formed to cover at least inner walls of the openingportion 12 of the housing 10. The reflector 40 may have the samematerial as the lead frame 20. That is, the reflector 40 may include abase metal layer, a light-reflecting layer including silver (Ag) oraluminum (Al), and a protection layer including gold (Au), nickel (Ni),or titanium (Ti) as shown in FIG. 3.

The reflector 40 and the lead frame 20 are supported by the housing 10.The reflector 40 may include light-reflecting portion 42 covering innerwalls of the opening portion 12 having inverted truncated cone shape,and a heat-radiating portion 44 extended from the light-reflectingportion 42 to be disposed out of the housing 10.

The light-reflecting portion 42 is inclined, since the opening portion12 has an inverted truncated cone shape in which an upper diameter isgreater than a lower diameter. The shape of the light-reflecting portion42 corresponds to the inner walls of the opening portion 12 of thehousing 10. Therefore, the light-reflecting portion 42 makes contactwith the inner wall of the opening portion 12.

The heat-radiating portion 44 is extended from the light-reflectingportion 42 to be exposed out of the housing 10. For example, theheat-radiating portion 44 is extended from an upper end portion of thelight-reflecting portion 42 to a side of the housing 10. The housing 10may include a heat-radiating hole 13 formed at a side of the housing.

When the number of the heat-radiating portions 44 increases,heat-radiating characteristics of the LED may be improved. Theheat-radiating portion 44 has a strip shape extended from a portion of acircumference of an upper portion of the light-reflecting portion 42.Alternatively, the heat-radiating portion 44 may be extended from aportion of a circumference of a lower portion or the inner wall betweenthe upper and lower portions. Furthermore, the heat-radiating portion 44may have a torus shape extended from the entire circumference of thelight-reflecting portion 42.

As long as the reflector 40 surrounds the opening portion 12 of thehousing 10, the reflector 40 may have various shapes.

FIG. 29 is a plan view showing an LED according to still anotherexemplary embodiment of the present invention, and FIG. 30 is across-sectional view showing the LED in FIG. 29.

Referring to FIG. 29 and FIG. 30, an LED includes a lead frame havingfirst and second lead terminals 210 and 220, a light-emitting chip 300,a conducting wire 400, a housing 510 and an encapsulant 600.

The first and second lead terminals 210 and 220 apply electric power tothe light-emitting chip 300. The first and second lead terminals 210 and220 include a base metal layer, a light-reflecting layer includingsilver (Ag) or aluminum (Al), and a protection layer including gold(Au), nickel (Ni), or titanium (Ti).

The light-emitting chip 300 is mounted on the first lead terminal 210,and electrically connected to the second lead terminal 220 through theconducting wire 400.

The housing 510 has an opening portion 520 for exposing thelight-emitting chip 300 and portions of the first lead terminal 210 andsecond lead terminal 220. The opening portion 520 may have an invertedtruncated cone shape. That is, the opening portion 520 has a decreasingsize along a direction from an upper portion of the housing 510 to alower portion of the housing 510.

Additionally, the housing 510 includes a cleavage portion 530 forexposing a wire bonding region. For example, a portion of the openingportion 520 is depressed to form the cleavage portion 530. The cleavageportion 530 is formed at a region of the opening portion 520, whichexposes a portion of the second lead terminal 220 so that thelight-emitting chip 300 is electrically connected to the portion of thesecond lead terminal 220 through a wire 400. In detail, thelight-emitting chip 300 is mounted on the first lead terminal 210, andelectrically connected to the first lead terminal 210 by making contactwith the first lead terminal 210, and the light-emitting chip 300 iselectrically connected to the second lead terminal 220 exposed throughthe cleavage portion 530 which is formed by recessing a portion of theopening portion 520 of the housing 510.

The shape and size of the wire bonding region of the second leadterminal 220 may be adjusted, considering the shape and size of thecleavage portion 530. When the number of the conducting wire 400 is morethan one, or the number of the light-emitting chip 300 is more than one,the number of the cleavage portion 530 may be plural, corresponding tothe number of the conducting wire 400.

The encapsulant 600 fills the opening portion 520 of the housing 510 andthe cleavage portion 530 to protect the light-emitting chip 300.

Not shown in the FIG. 29 and FIG. 30, the reflector may be formed on theinner wall of the opening portion 520 and cleavage portion 530.

As described above, when the cleavage portion 530 for wire bonding isformed at a portion of the housing 510, the size of the housing 510 maybe reduced, while securing a space for wire bonding to minimize defectsof the wire bonding.

FIG. 31 is an exploded perspective view showing a backlight unitaccording to an exemplary embodiment of the present invention.

Referring to FIG. 31, a backlight unit according to an exemplaryembodiment of the present invention includes a light guide plate 310 andat least one LED 320 disposed adjacent to the light guide plate 310 toprovide the light guide plate 310 with light.

The LED 320 may be mounted on a circuit board 330 such as a printedcircuit board (PCB) or a flexible printed circuit board FPCB. Forexample, a plurality of LEDs 320 is arranged along a longitudinaldirection of the circuit board 330 with uniform distance. The LEDs 320emit light with the LEDs 320 to receive electric power through thecircuit board 330.

The LEDs 320 may be one in FIGS. 1 through 30. Therefore, any furtherexplanations regarding to the LEDs 320 will be omitted.

The light guide plate 310 receives light generated by the LEDs 320through a side surface and emits the light toward a liquid crystaldisplay (LCD) panel disposed over the backlight unit. Preferably, thelight guide plate 310 includes optically transparent material in orderto minimize light loss. The light guide plate 310 may include, forexample, polymethyl methacrylate (PMMA) or polycarbonate (PC).

The light guide plate 310 may have light-reflecting patterns (not shown)formed on a lower surface of the light guide plate 310. For example, thelight-reflecting patterns formed on a lower surface of the light guideplate 310 may be printed patterns or embossing patterns. Therefore,light entering the light guide plate 310 from the LED 320 may bediffusively reflected by the light-reflecting pattern, and portions ofthe lights arrive at an upper surface of the light guide plate 310 withan angle smaller than the critical angle with respect to a normal lineof the upper surface exit the light guide plate 310 through the uppersurface of the light guide plate 310.

The light guide plate 310 may have uniform thickness. That is, anincident surface of the light guide plate 310, through which lightgenerated by the LED 320 enters the light guide plate 310, may have thesame width as an opposite surface of the incident surface.Alternatively, the light guide plate 310 may have a wedge shape havingdecreasing thickness in a direction from the light incident surface tothe opposite surface.

The backlight unit may further include a light-reflecting sheet 340disposed under the light guide plate 310. The light-reflecting sheet 340reflects light that leaks out from the light guide plate 310 through thelower surface toward the light guide plate 310 to enhance light-usingefficiency. The light-reflecting sheet 340 may include white-coloredpolyethylene terephthalate (PET) or polycarbonate (PC).

The backlight unit may further include optical sheets 350 disposed overthe light guide plate 310. The optical sheets 350 may include at leastone of a light-diffusing sheet diffusing light to enhance luminanceuniformity, a light-condensing sheet enhancing front-view luminance, anda reflective polarization sheet enhancing luminance by recycling oflight.

It will be apparent to those skilled in the art that variousmodifications and variation can be made in the present invention withoutdeparting from the spirit or scope of the invention. Thus, it isintended that the present invention cover the modifications andvariations of this invention provided they come within the scope of theappended claims and their equivalents.

What is claimed is:
 1. A lead frame, comprising: a first lead terminaland a second lead terminal spaced apart from each other, each of thefirst lead terminal and the second lead terminal comprising: a basemetal layer; a light-reflecting layer arranged directly on the basemetal layer; and a protection layer arranged directly on thelight-reflecting layer and comprising a metal, wherein the protectionlayer is the outermost layer of the lead frame, and wherein the firstlead terminal and the second lead terminal are configured to applyelectric power to a light emitting chip.
 2. The lead frame of claim 1,wherein the light-reflecting layer comprises silver (Ag) or aluminum(Al).
 3. The lead frame of claim 1, wherein the protection layercomprises gold (Au), nickel (Ni), or titanium (Ti).
 4. The lead frame ofclaim 3, wherein the protection layer comprises gold (Au) and is 0.1 nmto 600 nm thick.
 5. The lead frame of claim 3, wherein the protectionlayer comprises nickel (Ni) or titanium (Ti) and is 0.1 nm to 20 nmthick.
 6. The lead frame of claim 1, further comprising a nickel layerarranged between the base metal layer and the light-reflecting layer. 7.The lead frame of claim 6, wherein the nickel layer is arranged directlyon the base metal layer, the light-reflecting layer is arranged directlyon the nickel layer, and the protection layer is arranged directly onthe light-reflecting layer.
 8. The lead frame of claim 1, wherein thebase metal layer comprises Cu.
 9. The lead frame of claim 1, wherein thethickness of the base metal layer is about 0.1 mm to 1.0 mm.
 10. Abacklight unit, comprising: a light guide plate; and at least one lightemitting diode (LED) to provide the light guide plate with light,wherein the at least one LED comprises: a lead frame comprising a basemetal layer, a light-reflecting layer arranged directly on the basemetal layer, and a protection layer arranged directly on thelight-reflecting layer and comprising a metal; and a light-emitting chiparranged on the lead frame, wherein the protection layer is theoutermost layer of the lead frame.
 11. The backlight unit of claim 10,wherein the light-reflecting layer comprises silver (Ag) or aluminum(Al).
 12. The backlight unit of claim 10, wherein the protection layercomprises gold (Au), nickel (Ni), or titanium (Ti).
 13. The backlightunit of claim 10, wherein the base metal layer comprises Cu.
 14. Thebacklight unit of claim 10, wherein the thickness of the base metallayer is about 0.1 mm to 1.0 mm.
 15. A lead frame, comprising: a basemetal layer; a light-reflecting layer arranged on the base metal layer;and a protection layer arranged on the light-reflecting layer andcomprising a metal, wherein the light-reflecting layer and theprotection layer are arranged on a first side of the base metal layerand a second side of the base metal layer opposite to the first side,and wherein the protection layer is the outermost layer of the leadframe.
 16. A lead frame, comprising: a first lead terminal and a secondlead terminal spaced apart from each other, each of the first leadterminal and the second lead terminal comprising: a base metal layer; alight-reflecting layer arranged on the base metal layer; and aprotection layer arranged on the light-reflecting layer and comprising ametal, wherein the light-reflecting layer and the protection layer arearranged on the entire length of the base metal layer, and wherein theprotection layer is the outermost layer of the lead frame, and whereinthe first lead terminal and the second lead terminal are configured toapply electric power to a light emitting chip.
 17. A backlight unit,comprising: a light guide plate; and at least one light emitting diode(LED) to provide the light guide plate with light, wherein the at leastone LED comprises: a lead frame comprising a base metal layer, alight-reflecting layer arranged on the base metal layer, and aprotection layer arranged on the light-reflecting layer and comprising ametal, wherein the light-reflecting layer and the protection layer arearranged on a first side of the base metal layer and a second side ofthe base metal layer opposite to the first side; and a light-emittingchip arranged on the lead frame, wherein the protection layer is theoutermost layer of the lead frame.
 18. A backlight unit, comprising: alight guide plate; and at least one light emitting diode (LED) toprovide the light guide plate with light, wherein the at least one LEDcomprises: a lead frame comprising a base metal layer, alight-reflecting layer arranged on the base metal layer, and aprotection layer arranged on the light-reflecting layer and comprising ametal, wherein the light-reflecting layer and the protection layer arearranged on the entire length of the base metal layer, wherein alight-emitting chip is arranged on the lead frame, and wherein theprotection layer is the outermost layer of the lead frame.